[webrtc-stats] RTX and FEC stats are incomplete. (#751)

fippo has just created a new issue for https://github.com/w3c/webrtc-stats:

== RTX and FEC stats are incomplete. ==
While we have statistics about retransmission [packetsSent](https://w3c.github.io/webrtc-stats/#dom-rtcoutboundrtpstreamstats-retransmittedpacketssent) and [bytesSent](https://w3c.github.io/webrtc-stats/#dom-rtcoutboundrtpstreamstats-retransmittedbytessent) on [outbound-rtp](https://w3c.github.io/webrtc-stats/#dom-rtcstatstype-outbound-rtp) stats, we lack corresponding `retransmittedPacketsReceived` and `retransmittedBytesReceived` for [inbound-rtp](https://w3c.github.io/webrtc-stats/#dom-rtcstatstype-inbound-rtp).

I *believe* the reason is that without RTX it is not possible to identify retransmissions. However, RTX is available in all browsers these days (for video). When RTX is not used, these should not be present. #735 defines those.

Similarly, for FEC we have `inbound-rtp` stats for [fecPacketsReceived](https://w3c.github.io/webrtc-stats/#dom-rtcinboundrtpstreamstats-fecpacketsreceived) and [fecPacketsDiscarded](https://w3c.github.io/webrtc-stats/#dom-rtcinboundrtpstreamstats-fecpacketsdiscarded) but no corresponding `outbound-rtp` `fecPacketsSent` and no `fecBytesSent`. We also lack `fecBytesReceived`.

I *believe* this is due to FEC focusing on opus inband audio fec where the amount of bytes is somewhat hard to calculate *because opus*. For video FEC we have both `ulpfec` and `flexfec` implemented in browsers but don't have good statistics on them.

Please view or discuss this issue at https://github.com/w3c/webrtc-stats/issues/751 using your GitHub account

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Received on Thursday, 30 March 2023 18:27:14 UTC